The present invention relates to a magnetic recording signal reproducing apparatus of a digital system and, more particularly, to a control unit of a magnetic tape and a magnetic head.
As a head control technique, an apparatus in which a moving mechanism is added to a reproducing head and the reproducing head is moved in the width direction of a track and a tracking error is prevented has been disclosed in, for instance, JP-B-63-19929 as a published Official Gazette of Japanese Patent Application filed by Sony Corporation on Mar. 13, 1980. On the other hand, apparatuses for controlling a tape tension to prevent a decrease in reproduction signal level due to a lack of tension of a tape which runs have been disclosed in JP-A-64-82356 as a published Official Gazette of Japanese Patent Application filed on Sep. 25, 1987, by Hitachi Ltd., JP-A-62-267955 as a published Official Gazette of Japanese Patent Application filed on May 15, 1986, by Sony Corporation, and JP-A-1-317255 as a published Official Gazette of Japanese Patent Application filed on Jun. 17, 1988, by Hitachi Electronics Co., Ltd.
In the magnetic recording/reproducing apparatus of the helical scan type, magnetic heads for recording and reproduction are attached to a rotary cylinder, a magnetic tape is wound around the cylinder and is run, and the recording and reproduction are executed. In the reproducing mode, there are problems such as defective reproduction which occurs because the magnetic tape is not closely adhered to the cylinder surface, defective reproduction due to a curve of a recording track, and deterioration in picture quality by a noise bar which occurs in the case of reproducing at a tape speed different from a recording tape speed as in the searching mode.
In the conventional apparatuses, the optimum control cannot be selected in accordance with all of the causes of the defective reproduction.